Microwave dielectric ceramic of LiZnPO4 for LTCC applications

The feasibility of LiZnPO4 (LZP) ceramic prepared by a solid-state reaction method for low-temperature co-fired ceramic application was investigated. Dense ceramic with 94.37% relative density was obtained when the ceramic was sintered at 850 A degrees C for 4 h. The LZP ceramic sintered at 850 A degrees C for 4 h possessed a relative permittivity (epsilon(r)) of 5.3 and high quality factor (Q x f) of 28,496 GHz (at 12.9 GHz) with a temperature coefficient of resonant frequency (tau (f) ) of -80.4 ppm/A degrees C. The relatively large negative tau (f) value was reduced by adding TiO2 into LZP ceramics. The microstructure, microwave dielectric properties and cofiring compatibility with silver of LZP-TiO2 composites were discussed. The composite with 0.17 volume fraction of TiO2 sintered at 950 A degrees C for 4 h shows epsilon(r) = 10.0, Q x f = 10,025 GHz, tau (f) = +1.6 ppm/A degrees C. The LZP-TiO2 composite was chemically compatible with the commonly used electrode material silver.